CHICAGO (CBS) -- Investigators are working to
determine if a shipment of 18 human heads intercepted by customs
officials at O'Hare International Airport are, in fact, legitimate medical specimens,
authorities said Tuesday morning.

The heads, sent to Chicago from outside the U.S., were discovered
Monday by U.S. Customs officials and appear to be medical samples at
first blush, said Brian Bell, a Chicago-based spokesman for the
Department of Homeland Security.

"There's no issue with the transportation of body parts for medical
purposes," Bell said. "There's nothing against the law that says you
cannot ship them, provided you have the right documentation."

While Bell said he has never before fielded questions about a large
package of human body parts, such shipments are not without precedent,
he noted.

"Everybody here is 'Oh my gosh, you got a box of heads' and everybody
thinks that it's unheard of," Bell said. "It is a potentially
legitimate medical shipment. We've seen it at various ports in the
nation."

Bell declined to say where the package was shipped from, where its
intended destination is, or how the heads were packaged and preserved.

The specimens, which are still covered in skin, were sent to the Cook
County Medical Examiner's office for inspection, authorities said. Foul
play was not involved in the collection of the heads

"We need to make sure that they are truly used for medical research purposes," said Bell.